Recovery in 15%Cr Ferritic Stainless Steel after Large Strain Deformation

Abstract:

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15%Cr ferritic stainless steel was machined in rectangular samples and then processed by
multiple forging to a total cumulative strain of 7.2 at an ambient temperature. The large strain
deformation resulted in almost equiaxed submicrocrystalline structure with a mean grain/subgrain
size of 230 nm and about 2.2×1014 m-2 dislocation density in grain/subgrain interiors. The annealing
at a relatively low temperature of 500oC did not lead to any discontinuous recrystallizations. The
grain/subgrain size and the interior dislocation density slightly changed to 240 nm and 2.1×1014 m-2,
respectively, after annealing for 30 min, while the Vickers hardness decreased from 3140 MPa in
the as-processed state to 2900 MPa. This annealing softening was attributed to remarkable release
(by 50%) of internal stresses, which are associated with a non-equilibrium character of
strain-induced grain/subgrain boundaries.

Abstract: Nearly equi-atomic Ni-Ti alloys (nitinol) show shape memory behavior, superelasticity, high strength, excellent corrosion resistance and biocompatibility, making them of interest for various biomedical applications. In processing, they experience various heat treating steps. The present work illustrates influence of a short-time heat treatments (several minutes) at moderate temperatures (around 500°C) on transformation temperature Af and on mechanical properties.

Abstract: The development of texture and grain boundary character are researched for a boron bearing IF steel after recrystallization annealing for different times at 810°C. The results show that the main texture components are {111}<110> and {111}<112> after the cold rolling samples annealing different times. The maximal volume fraction of <111>//ND texture is about 78% for the sample annealing for 120sec. The main CSL boundaries are ∑3，∑5，∑7，∑9，∑11，∑13b and ∑17b. And the ∑3 grain boundary increase with increasing the annealing times from 60sec to 180sec.

Abstract: In the present study, a modified cellular automaton CORe (Cellular Operator for Recrystallization) was used to predict the recrystallization (RX) texture and microstructure of 70% cold rolled commercial AA8079L alloy at 300°C. The nucleation of the Cube orientation is of considerable scientific interest since the Cube texture component influences significantly the anisotropy of material properties. Experimental data collected during this investigation were used for subsequent modeling. By studying the annealed material by EBSD, an average nucleation rate at Cube bands was established and used in the model. The simulated microstructure reveals, in general, good agreement with experiment. The texture prediction shows the right tendency, but the modeled intensity of the Cube texture is about 2 times smaller than in experiment.

Abstract: The recrystallization behavior of the cold rolled 3%Si nonoriented electrical steel at different temperatures is investigated by OIM(Orientation Imaging Microscopy). The results show that the recrystallization process and texture of 3%Si nonoriented electrical steel at different temperatures are determinated by different recrystallization mechanisms. At low annealing temperatures, the formation of recrystallization texture in this specimen can be explained by the mechanism of oriented nucleation theory, but at higher annealing temperatures, the formation of recrystallization texture in this specimen can be explained by the mechanism of oriented growth theory, the twin nucleation mechanism may penetrate the whole recrystallization process.